The only way I can do this is if I have a 1/4
inch Jack.

lets say this.

I get this 1/4 inch Jack line plug thingy.

do I have to have a stereo that has a mic plug in.

I could not plug in my plug out of my Keyboard to the head phones of my stereo.
my stereo does not have a mic plug in
My stereo type is a iawa. and is has a skinny hole that you plug the head phones in.

these are my questions

How much does something like this usually cost?

Do I have to plug the line out of the keyboard to the Mic. Or does it matter if I put it in the phones of the stereo.

Thanks a lot